The research outlined in this proposal will examine interactions occurring between ethanol and the metabolic activation of chemical carcinogens. Isolated perfused livers and hepatocytes will be used for these experiments because the activation, conjugation and binding of carcinogens to cellular macromolecules can be studied simultaneously under near physiological conditions. This research will be directed at three major objectives. 1) The influence of chronic ethanol administration on pathways of mixed-function oxidation and conjugation in intact cells will be determined. The effects of altered intermediary metabolism associated with ethanol feeding on the biosynthesis of cofactors required for both processes will also be evaluated. 2) The influence of the acute addition of ethanol on carcinogen activation will be studied. Direct effects on ethanol on enzymes will be differentiated from indirect effects caused by the metabolism of ethanol and subsequent interactions with pathways of cofactor biosynthesis. 3) The effects of carcinogen exposure on pathways of mixed-function oxidation, conjugation, ehtanol metabolism and related metabolic processes will also be assessed. These studies will utilize model carcinogens (e.g., benzo(a)pyrene and dimethylnitrosamine) and non-carcinogenic substrates for the various mixed-function oxidase and conjugation pathways. Changes in binding of carcinogens to macromolecules will be compared to changes in enzyme activities, altered concentrations of intracellular intermediates, and local changes in metabolism detected by surface fluorescence. In this manner, rate-limiting steps for carcinogen metabolism in intact cells will be established. An increased risk of cancer in heavy consumers of ethanol has been recognized as significant health problem. Moreover, studies already completed have demonstrated interactions occurring between both acute and chronic exposure to ethanol and rates of mixed-function oxidation and conjugation which are involved in the metabolism of carcinogens. The proposed studies will focus on defining molecular mechanisms by which ethanol may increase the risk of cancer from chemical carcinogens.